Lyle A. Norwood

The anatomy of the iliopatellar band and iliotibial tract

Based on an extensive review of the literature and dissections of 17 fresh-frozen knee specimens, the authors divide the lateral fascia lata of the knee into two functional components: the iliopatellar band and the iliotibial tract. Aponeurotic, superficial, middle, deep, and capsulo-osseous layers contribute to these two functional components. The superficial layer of the iliotibial tract, combined with the deep, and capsulo-osseous layers, is hypoth esized to function as an anterolateral ligament of the knee. The iliopatellar band provides stabilization of the patella against a medially directed force and is dynam ically influenced by the vastus lateralis. The relationship of the iliotibial tract to extraarticular reconstructions of the knee with anterolateral rotatory instability is discussed.

The posterolateral drawer test and external rotational recurvatum test for posterolateral rotatory instability of the knee

Posterolateral drawer tests and external rotational recurvatum tests are used to detect posterolateral rotatory instability. A specific manner of performance of these tests is necessary to properly interpret the nature of acute and chronic knee conditions. The posterolateral drawer test is performed at 80 degrees of knee flexion and is maximum in 15 degrees of external rotation. Since the posterior cruciate ligament is intact in posterolateral rotatory instability, the posterior drawer will be negative on maximum internal tibial rotation. Fibrous scar tissue may conceal an otherwise positive posterolateral drawer sign in the chronic condition. The external rotational recurvatum test examines the knee in extension. Tightness and spasm of the biceps femoris and semimembranosus may obscure a positive external rotational recurvatum test in the acute or chronic condition. The external rotational recurvatum test will be negative when the anteromedial and intermediate bundles of the anterior cruciate ligament are intact owing to their contact with the intercondylar shelf in extension. The posterolateral drawer and the external rotational recurvatum can be subtle tests and require careful observation for accurate evaluation of both the acute or chronic condition of the knee joint.

The stabilizing function of passive shoulder restraints

The static restraints of the scapulohumeral joint provide stability for the humeral head in the glenoid cavity, limit extremes of motion of the glenohumeral joint, and guide positioning of the humerus during normal shoulder movement. Eleven fresh-frozen cadaver shoulders of unknown age were attached to a shoulder motion device that allowed measurement of motion in three planes with an accuracy to 0.5°. Four shoulders underwent motion analysis and seven were used for strain gauge analysis of the static scapulohumeral ligamentous restraints. The results of the motion analysis demonstrated that any attempt at simple motion (flexion, extension, ab duction, internal or external rotation) resulted in coupled motion in two additional planes. The strain gauge data, expressed as a percent of total tension for each ligament tested, demonstrated a reciprocal tension-sharing relationship among all liga ment components and a transference of tension among these components when original and new joint posi tions were compared. These data provide an in vitro model of shoulder restraint function to explain primary restraint, tension sharing, and transference of tension functions in the in vivo scapulohumeral joint. Clinical relevance: These principles of shoulder func tion have application in the treatment of instability and frozen shoulder syndrome, and provide an in vitro model to better understand static restraint function in the throwing mechanism.

Anterior cruciate ligament: functional anatomy of its bundles in rotatory instabilities.

The functional anatomy of the anterior cruciate ligament was studied in 18 freshly amputated specimens. The cruciates were observed in the extremes of flexion and extension, and in midposition in simulated weight-bearing and nonweight-bearing conditions. Five femoral shafts were split longitudinally so that the femoral and tibial attachments of the ligament could be inspected. The findings indicated that (1) the anterior cruciate ligament is a secondary static stabilizer against rotatory in stabilities of the knee; (2) the anteromedial bundle contributes to anterolateral stability; (3) the intermediate bundle adds to straight and anteromedial stability; and (4) the posterolateral bundle assists in posterolateral stability. Specific bundles and functions of bundles must be considered in reconstruction, substitution, or replacement of the anterior cruciate ligament.

Acute combined posterior cruciate and posterolateral instability of the knee

This report concerns 13 consecutive patients (13 knees) who underwent operative treatment for acute combined posterior cruciate and posterolateral instabil ity due to combined injury to the posterior cruciate ligament and the arcuate ligament complex. Our pur pose was to examine the method of diagnosis and the results in these patients. There were 12 males and 1 female (average age, 26 years). Five patients were injured in a motor vehicle accident, four in sports activ ities, and four in nonsports activities. The mechanism of injury was an anteromedial blow to the flexed knee in six patients, a fall onto the knee in two, and unknown in five patients. Eleven patients were available for fol low-up evaluation (average, 56 months), and in each the result was rated as good, fair, or poor. In 10 patients (90%) the results were rated as good subjectively, in 11 (100%) as good functionally, and in 8 (73%) as good objectively. Injury to both the posterior cruciate liga ment and the arcuate ligament complex can result from rotational force that can be due to a blow to the anteromedial aspect of the knee. Diagnosis can be made by a combined positive response to the posterior drawer test, the anterior drawer test performed with the tibia in internal rotation, the abduction and adduc tion stress tests performed with the knee in full exten sion, the posterolateral drawer test, and the external rotation-recurvatum test. In a knee with concomitant injury to the posterior cruciate ligament and the arcuate ligament complex that requires surgical repair, all in jured structures should be explored and repaired to ensure a subjectively, objectively, and functionally good result.

How iliotibial tract injuries of the knee combine with acute anterior cruciate ligament tears to influence abnormal anterior tibial displacement

A knowledge of the patterns of injury to the compo nents of the iliotibial tract allows a clearer interpretation of motion limits testing in patients with abnormal ante rior tibial translation of the knee (anterior cruciate liga ment-deficient knees). Eighty-two consecutive patients with acute knee in juries were classified as anteromedial-anterolateral ro tatory instability (anterior cruciate ligament-deficient) based on the abnormal motion demonstrated by clinical examination tests for instability. At surgery, injuries to the intraarticular and extraarticular anatomic structures were identified and correlated to the abnormal grades of motion demonstrated by the knee motion limits ex amination. Tears of the anterior cruciate ligament occurred in 80 (98%) of the knees. However, the grade of abnormal motion demonstrated by the Lachman and pivot shift tests was quite variable. This variation did not correlate statistically with anterior cruciate ligament tears. Injuries to the anatomic components of the iliotibial tract were confirmed in 76 (93%) of the knees. These injuries correlated highly with variations in grades of abnormal motion detected by the following tests: lateral joint line opening at 30° (r 2 = 0.05); Lachman test (r 2 = 0.08); pivot shift (r 2 = 0.16); and anterior translation at 90° of flexion (r 2 = 0.34). Thus, injuries to the components of the iliotibial tract are thought to contrib ute to the variation in grades of abnormal motion ob served in this complex subgroup of anterior tibial trans lation instabilities.

The intercondylar shelf and the anterior cruciate ligament

The anterior cruciate ligament is the only completely intraarticular knee ligament without capsular attachment, and this makes it impossible to examine its integrity directly. Therefore, the determination of injury to the anterior cruciate ligament relies upon the rapidity and character of clinical swelling, the mechanism of injury, and nonspecific tests of knee stability. The manner of contribution of the anterior cruciate ligament to knee stability and the interpretation of various tests of examination for anterior cruciate disruption are confusing.

Acute medial elbow ruptures

Disruption of the ulnar collateral ligament, flexor mus cles, and anterior elbow capsule may result from valgus vector forces and subsequently cause difficulty in throwing, pulling, pushing and catching. Complete medial elbow tears were diagnosed acutely in four elbows by abduction stress tests at 15° of flexion. Three elbows had associated ulnar nerve compres sion. We repaired torn medial structures by direct suture without ligamentous reconstruction. We also decompressed ulnar nerves and performed one an terior transposition. Full range of motion, strength, and return to previous functional level was attained without infection, neurovascular compression, or my ositis ossificans.

Shoulder posterior subluxation

The records of 21 patients with chronic recurrent pos terior subluxation were reviewed to document postop erative stability and level of athletic participation after opening wedge posterior scapular osteotomy and as sociated soft tissue procedures. At an average of 39.9 months after surgery, we objectively reevaluated 17 males and 2 females (from 16 to 46 years old). Patients with posterior instability caused by a direct trauma stabilized and effectively returned to athletic participa tion following osteotomy. Patients with posterior stabil ity resulting from muscular contraction required addi tional soft tissue procedures for stability and effective return to athletics. Congenitally or habitually lax shoul ders did not stabilize in this series. This study suggests that opening osteotomy is indi cated for single plane, posterior instability which results from direct trauma or muscular contraction, and for combined anterior-posterior instability. Opening oste otomy is contraindicated in congenitally or habitually lax shoulders. A descriptive classification system which groups shoulders according to injury force and direction of instability facilitates preoperative prediction of sub sequent glenohumeral joint stability and athletic partic ipation or level of nonsportive activity.

Ulnar nerve entrapment syndrome in baseball players

Ulnar nerve entrapment at the elbow has been described in the literature. This paper deals with 19 skeletally mature baseball play ers with ulnar nerve entrapment who under went surgery for correction of the problem. The surgery consisted of anterior transfer of the nerve and placement deep to the flexor muscles. Six players quit baseball because of continuing elbow problems, nine returned to playing, and four were lost to follow-up. Ulnar nerve entrapment is thought to represent one syndrome in a spectrum of diseases involving the medial side of the elbow in baseball play ers. The lesion is amenable to surgery.